Using the computer or watching television late at night can cause symptoms similar to depression, according to a new study, published in the journal Molecular Psychiatry (Photo: flickr.com/fakelvis)

Using the computer or watching television late at night can cause symptoms similar to depression, according to a new study, published in the journal Molecular Psychiatry. Researchers said the findings add to the mounting evidence that chronic exposure to artificial light is responsible for the rising rates of depression over the past 50 years.

One in 20 Americans over the age of 12 reported feeling symptoms of depression between 2005 and 2006, according to the Centers for Disease Control and Prevention. Symptoms include hopelessness, feeling like a failure, poor appetite and lack of interest in activities.

Like Us on Facebook

Researchers found that rodents exposed to dim light at night showed evidence of depressive symptoms after just four weeks.

"The results we found in hamsters are consistent with what we know about depression in humans," Tracy Bedrosian, study author and doctoral student in neuroscience at Ohio State University, said in a statement.

A particular protein found in the brain of hamsters -- and humans - may play a role in how nighttime-lights can lead to depression. The light increased the production of the protein "tumor necrosis factor," which is typically mobilized when the body suffers an injury. TNF causes inflammation, which can be damaging when it is constant.

"Researchers have found a strong association in people between chronic inflammation and depression," Randy Nelson, study coauthor and professor of neuroscience and psychology, said in a statement. "That's why it is very significant that we found this relationship between dim light at night and increased expression of TNF."

The good news, researchers said, is that research showed that the depressive symptoms can be reversed.

"The good news is that people who stay up late in front of the television and computer may be able to undo some of the harmful effects just by going back to a regular light-dark cycle and minimizing their exposure to artificial light at night," Bedrosian said. "That's what the results we found in hamsters would suggest."